Aviation safety investigations & reports

de Havilland Canada DHC-8-102, VH-TQR

Summary

On 19 February 2005 at 1310 Eastern Daylight-saving Time, a de
Havilland Canada DHC-8-102 aircraft, registered VH-TQR, was being
operated on a scheduled regular public transport service from
Canberra, ACT, to Sydney, NSW. On arrival at the terminal the crew
was given marshalling instructions from ground staff to taxi onto
bay 57R and stop. The pilot in command (PIC) then reversed the
aircraft until instructed to stop by an off-duty marshaller who had
seen that the tail of the aircraft was very near to the Terminal 2
building.

Factaul Information

On 19 February 2005 at 1310 Eastern Daylight-saving Time, a de
Havilland Canada DHC-8-102 aircraft, registered VH-TQR, was being
operated on a scheduled regular public transport service from
Canberra, ACT, to Sydney, NSW. On arrival at the terminal the crew
was given marshalling instructions from ground staff to taxi onto
bay 57R and stop. The pilot in command (PIC) then reversed the
aircraft until instructed to stop by an off-duty marshaller who had
seen that the tail of the aircraft was very near to the Terminal 2
building.

While en route to Sydney, the crew had contacted the operator's
movement control officer to request a parking bay and to advise
that the weather radar was unserviceable. The crew were advised to
expect a 'reverse bay'. The crew discussed the requirement to park
on a reverse bay. They were uncertain if the aircraft was to be
reversed onto the correct stopping point. There was no discussion
about the marshalling signals they would expect to see. The PIC
referred to the aircraft's parking bay diagrams (see Appendix A),
and was satisfied that the lead in lines painted on the tarmac and
the signals of the marshaller would provide sufficient
guidance.

After vacating runway 34 left, the crew was advised by the
operator to park on bay 57 reverse (57R) so that engineers could
repair the weather radar. Bay 57R is located near the southern end
of Terminal 2 Pier B (see Figure 1) and required aircraft to park
with the nose pointing away from the terminal.

Figure 1: Parking bay 57 (for illustrative
purposes only)

The bay is also marked 57A for aircraft parked facing the
terminal. Bay 57R was used to park aircraft in conditions of strong
westerly winds, or if engineering staff required the nose of the
aircraft to be facing away from the terminal building. The bay was
commonly referred to by both ground staff and flight crew as 57
reverse or a reverse parking bay.

The PIC taxied the aircraft to Bay 57R, where it was marshalled
into position and stopped by the crew when they observed the
marshaller cross his arms once at approximately chest height. The
position of the aircraft at that stage was correct for Bay 57R.
However, the crew were concerned that the aircraft was positioned
too close to a vehicle access road marked on the movement area and
after briefly discussing between themselves the meaning of the
signal used by the marshaller, decided that the instruction was to
reverse. The PIC then reversed the aircraft and anticipated that
the marshaller would signal them to stop at the correct point. The
crew noted that the marshaller was walking toward the aircraft as
it reversed, using hand signals which they interpreted as
confirmation of the reverse manoeuvre, but which the marshaller
intended as a signal to stop.

The marshaller had been told that the aircraft had a problem
with the weather radar, which required that the ground power unit
(GPU) be positioned away from the aircraft's nose. When the
aircraft started to reverse the marshaller thought the crew were
also positioning the aircraft away from the GPU.

Three off-duty marshallers were in a lunch room, adjacent to bay
57R, when the shift supervisor observed the aircraft being
marshalled onto the bay. He then saw the aircraft reversing and
alerted the other two marshallers in the room to the situation.
They observed the aircraft marshaller signal the PIC to stop the
aircraft, by crossing his arms repeatedly at chest height. One of
the off-duty marshallers ran out onto the tarmac to the aircraft's
two o'clock position1
and signalled the crew to stop by crossing his arms over his head.
The tail of the aircraft was estimated by that off-duty marshaller
to be within 1 m of the terminal. The shift supervisor also went
onto the tarmac and marshalled the aircraft forward to the correct
bay 57R stop position.

The on-duty aircraft marshaller had received training on
aircraft ground marshalling in accordance with the operator's ramp
handling course document. The description for 'stop' in that
document was in accordance with the Civil Aviation Safety Authority
Civil Aviation Order (CAO) 20.3 Issue 5, Air Service
Operations, Marshalling and Parking of Aircraft.

Stop is indicated by the arms to be repeatedly crossed
above the head. (the rapidity of the arm movement related to the
urgency of the stop, ie. the faster the movement the quicker the
stop).

Other documentation used by the operator that included
marshalling signals were a Customer Service Ground Handling Manual
and a Flight Deck Engineering Manual that both stated:

Arms extended to full length above head in vertical
position with bats or wands held steady. Widely accepted signal for
use when there is no urgent stop requirement.

Although not in accordance with CAO 20.3, this signal
was recognised by ground staff and by flight crew to indicate
stop.

All of the manuals reviewed as part of the investigation stated
that marshalling bats should be used to minimise the risk of
misinterpretation. However, marshalling conducted by the operator
during daylight was conducted without the use of marshalling
bats.

1.The numbers on
a clock are used to describe relative position, where 12 o'clock is
directly in front. For example, a person or object observed abeam
to the left of an aircraft would be said to be at 9
o'clock.

Analysis

Although uncertain as to the meaning of 'reverse bay', the
flight crew thought the term was used to indicate the method of
positioning the aircraft on the bay. Any uncertainty about the
reverse manoeuvre should have been resolved by the crew before the
aircraft was reversed.

The stop signal used by the marshaller was ambiguous as the arms
were repeatedly crossed at chest height and not over the head. The
operator's ground handling manuals included information that the
use of marshalling bats would minimise the risk of
misidentification. The opportunity for any misinterpretation of the
stop signal used may have been minimised if marshalling bats had
been used in this instance.

The intervention of the off-duty marshaller was timely and
appropriate. Had he not taken this action, it is likely that the
aircraft would have collided with the terminal building. The crew's
uncertainty with parking on a reverse bay, and the marshaller's use
of an unfamiliar hand signal combined to create doubt in the minds
of the crew as to what the marshaller's intentions were.

Safety Action

As a result of this occurrence, the aircraft operator advised
the Australian Transport Safety Bureau that it would:

align all documents defining the marshalling process to comply
with the International Civil Aviation Organization standard and
issue instructions to staff to ensure compliance

use marshalling equipment when it is available

recommend to the airport operator that parking bays be
renamed.

In addition, The Civil Aviation Safety Authority advised that it
will take the following action:

ascertain if any airports have procedures that require aircraft
to reverse park on a bay

determine if any other airports use the term 'reverse bay'

ensure that the term 'reverse bay' is discontinued

discuss with operators the use of marshalling bats

ensure all operators use standard marshalling signals in
accordance with CAO 20.3.